Remove extra period in deprecation message

Author: aphedges

news/2A2E5A1E-F014-40E9-B0EF-0D9C4686358F.trivial.rst

@@ -836,7 +836,7 @@ def check_invalid_constraint_type(req: InstallRequirement) -> str:
                 "undocumented. The new implementation of the resolver no "
                 "longer supports these forms."
             ),
-            replacement="replacing the constraint with a requirement.",
+            replacement="replacing the constraint with a requirement",
             # No plan yet for when the new resolver becomes default
             gone_in=None,
             issue=8210,